Abstract:

Marine reserves are areas of the sea where fishing is not allowed. They provide refuges where populations of exploited species can recover and habitats modified by fishing can regenerate. In some places, closed areas have been used for fisheries management for centuries [1] and, until recently, natural refugia also existed, inaccessible through depth, distance or adverse conditions. Developments in technology have left few areas of fishing interest beyond our reach. Recently, the idea of marine reserves as fisheries management tools has re-emerged with developing interest in ecosystem-based management, and observations of incidental fisheries benefits from reserves established for conservation. In light of new evidence, we argue that, by integrating large-scale networks of marine reserves into fishery management, we could reverse global fishery declines and provide urgently needed protection for marine species and their habitats.

Extracts: the paper's two final sections:

How large should reserves be?

Examples discussed here show that reserves and closed areas work well across a size range spanning below 1 km2 to 5000 km2. The key to success is matching reserve size to the scales of movements of the organisms that they are designed to protect. For sedentary animals living on coral reefs, reserves of ,1km across have augmented local fisheries, especially where established in networks [16,21,52]. For more mobile estuarine fish, reserves in Florida (16 and 24 km2) have sustained spillover to local recreational fisheries for decades. Three closures totaling 17 000 km2 on Georges Bank have helped turn around long-term declines of several important exploited species).

The overall scale of protection is as important as the size of reserve units. Although closed areas in Newfoundland produced local benefits to lobster catches, at just 2% of fishing grounds, they have had a trivial effect on overall landings [54]. More than 40 theoretical and modeling studies have addressed the question of how much of the sea should be protected from fishing (reviewed in [26]). Depending on the fishery and conditions being considered, they conclude that fisheries benefits require closures of between 10 and 80% of fishing grounds. Most predict maximum benefits with closures of 20–40%. Intriguingly, the most convincing demonstrations of fishery benefits to date are mainly from places where coverage of protected areas falls into this approximate range: Apo Island (10%), Merritt Island (22%), Georges Bank (25%) Nabq (33%) and St Lucia (35%). For the three locations where data are available to make a judgment, Apo, Georges Bank and St Lucia, the ‘gold standard’ of higher overall catches with reserves than without, in spite of a reduced fishing area, appears to have been achieved (to date, for scallops only at Georges Bank). These bold initiatives uphold theoretical predictions that fishers will see improved catches where reserves of sufficient size are introduced to heavily exploited fisheries [2], and prove that effective enforcement is possible over a wide range of both reserve sizes and management sophistication. Of course, reserves on their own will not deliver sustainable fisheries.

We must complement them with reduced effort, decreased reliance on destructive fishing methods and clearer allocations of fishing rights and responsibilities. But by protecting and restoring the productive capacity of marine ecosystems, reserves can provide the bedrock on which other tools can build towards success.

Conclusions

Rapidly increasing evidence shows that reserves and fishery closures benefit species as diverse as molluscs [19,20], crustaceans [13,24,25] and fish of a wide variety of sizes, life histories and mobilities [3]. Benefits develop within two to five years of establishment and continue to build for decades. The examples we describe here show that reserves work in habitats as different as coral reefs, kelp forests, temperate continental shelves, estuaries, seagrass beds, rocky shores and mangroves [3].

Research on reserves is revealing the profound degree to which people have modified marine ecosystems by fishing. Nature conservation in the oceans cannot be achieved without marine reserves, neither, we would contend, can the world’s fisheries be made sustainable.

Fortunately, the evidence available suggests that we can design effective reserves for any habitat that is fished. At the World Summit on Sustainable Development in 2002, countries agreed ambitious targets for creating national networks of marine protected areas by 2012 and rebuilding overexploited fisheries by 2015†. Marine reserves offer a means to deliver on the first and contribute to the second promise.

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